Why Obito is a badly written character if some trolls like to use stupid term like pedo for him when both of them were almost the same age?
Why should we ignore the circumstances right before and after Rin's death? A young carefree idealist kid ends up horribly crippled and almost dead ( he would without Zetsu healing with half his body gone) in care of cunning schemer Madara. That much for psychological rehabilitation .. with final trigger of seeing friends die- always makes uchihas lose themselves.
I find the subsequent scene of the bloody and gory mayhem Obito causes when he loses himself-
"I'm in hell"
-one of the most profound words in the manga. Obito was standing with in a few inches deep pool blood and dead bodies all around him - once a kind kid, killing people in one of the most horrible ways possible and he didn't even notice when he did it. Only after the incident he stands there and takes in everything that happened. It brings the harsh reality of war near home. One sees not only their friends dying all around themselves but they realize how cruel they themselves can be - for the first time.
It's impossible to not be affected with something like that. How much and how it affects them depends on the individuals. How much they can cope with the harshness themselves and how much help they get. Madara showed him the easy way out-make a dream world where nothing happened and everything is just fine, along with filling his brain with own ideas of hate and injustice. In the dream world every one was under control and no one died, nothing bad happened.
"You let rin die" was just that- the trigger. Obito said it was not about Rin only but of course that panel won't suit for the bashing so it's ignore conveniently. Rin flash backs keep coming back because that's the last happy memory he had from his older life when everything was still nice and life was relatively innocent.
News flash: for Tobi/Obito the war was still on when he killed people so your logic can go both ways. It's not like he was randomly appearing in random civilian homes slitting few throats for fun without any purpose and disappearing.
How a character is written sometimes depends on how you want to focus on a character.
